I was recommended a great free source for Griffith’s Valuation at www.askaboutireland.ie
By searching ‘Matthew Young Waterford’ I was able find the following:
Tenant – Matthew Young
House and garden
value of land 12 shillings
Landlord – Board of Works
County – Waterford
Barony – Decies without Drum
Union – Waterford
Parish – Killea
Townland – Dunmore